Cocaine abuse is a rapidly growing medical proboem presenting neuropsychologists with a challenge to develop treatments which address its neuropsychological effects. However, there are presently no objective data in the literautre which describe the neuropsychological effects of chronic cocaine abuse. There are also no objective data describing the recovery from the neuropsychological effects of cocaine abuse or when treatment for cocaine abuse should end. The proposed study is the first to provide objective data which describe the nature, severity, and time course of neuropsychological impairments in recovering cocaine abusers. In the proposed study, the neuropsychological status of a group of npatients undergoing treatment for cocaine dependence will be evaluated repetedly (e.e., at 1-3, 7-9, 16-21, and 94-100 days from their last drug-taking episode) and contrasted with the neuropsychological staus of a group of inpatient alcoholics and a group of drug-free controls evaluated at comparable intervals. Neuropsychological functioning will be assessed in six major areas: CNS and ANS arousla, CNS and ANS reactivity, sensory functiioning, motor functioning, visual and auditory attention, and languate comprehension. Measures from both the behavioral (e.g., reaction time, detection rate) and electrophysiological (e.g., EEG, ERP) domains will be used.